Kristine Krug, Dept. of Physiology, Anatomy & Genetics, Oxford University

Identifying the neuronal signals responsible for perceptual decisions

Unique insights into the neuronal processes that shape perception and decision-making are obtained by directly recording signals from cortical neurons in macaque monkeys that are making perceptual judgements. Activity in single neurons in primate visual area V5/MT correlates trial-by-trial with perceptual decisions about the appearance of stereo-motion figures, which require the specific conjunction of more than one visual parameter. Weak electrical microstimulation of these neurons does not degrade visual performance; rather it biases the perceptual appearance of the stimulus, in a manner that is specific to the sensory selectivity of the neurons at the stimulation site. This evidence places these neurons on the causal path for decision-making. Decision signals in these neurons are thought to depend on the correlated activity of groups of behaviourally relevant neurons. We find that differing timescales of interneuronal correlations contribute to differences in such decision signals in area V5/MT, when we compare neuronal coding for a stereo-motion task with random motion stimulation. The longer time-scale associated with decisions about stereo-motion figures has the neural signature of a top-down influence onto V5/MT processing, which might convey and stabilize the perceptual signals for visual object appearance. Characterization of the spatio-temporal pattern of neuronal activations for perceptual decisions is a pre-requisite for effective control and repair of visual perception.

Organized by

Klaus Obermayer